1.
Fly me to the Moon*
On HW/SW used by Apollo missions to land on the Moon
April 1st 2015, Martin.Dvorak@mindforger.com* a song originally written by Brad Howard in 1954 and recorded by Frank Sinatra in1964

2.
Why?
Aim for deep space / universe understanding?
Aim for technological advance with huge impact on humanity?
Seek a solution to a crucial problem enabling humans to alive?
Another purely practical reason?
…

3.
Bring alien technology from the dark side of the Moon?
Why?

4.
Space Race as a part of Cold War propaganda

5.
Space Race Timeline

6.
Space Race Timeline: Computers Evolution
Intel founded 1968

7.
… 9x around the Moon & 6x on the Moon
Apollo Program: Mission(s) & Timeline
• Apollo 1 1966/02/22 - 1st flight of Saturn 1b
• Apollo 2 1966/07/05 - fuel tank test
• Apollo 3 1966/08/25 - sub-orbital Saturn 1b test
• Apollo 1 1967/01/27 - pre launch cabin fire (Block I)
• Apollo 4 1967/11/09 - 1st test of Saturn V booster
• Apollo 5 1968/01/22 - test of Saturn V booster & LM
• Apollo 6 1968/04/04 - test of Saturn V booster
• Apollo 7 1968/11/11 - 1st manned Saturn 1b
• Apollo 8 1968/12/21 - 1st manned Saturn V around Moon
• Apollo 9 1969/03/03 - 1st manned LM
• Apollo 10 1969/05/18 - 1st manned LM around Moon
• Apollo 11 1969/07/16 - 1st manned landing on the Moon
• Apollo 12 1969/12/14
• Apollo 13 1970/04/11 - SM explosion & LM as life boat
• Apollo 14 1970/01/31
• Apollo 15 1971/07/26 - 1st lunar rower excursion
• Apollo 16 1972/04/16
• Apollo 17 1972/12/07 - Final manned landing on M

8.
3 stages, 111m, service + lunar + command modules
AGC Drill Down: Saturn 5

9.
AGC Drill Down: Saturn 5
Žižkovská věž 213m

10.
Apollo PGNCS
• PGNCS == inertial guidance system
• Navigation (speed, position, attitude):
• Inertial: Inertial Measurement Unit - vector & gyroscope
• Optical: Optical Unit - sextant (position & orientation)
• Radio: Radar(s) - radio beacon & Doppler (v; 10mm/s)
• AGC == PGNCS computer
• Both on CM and LM
• Developed by MIT, manufactured by GM
The Primary Guidance, Navigation and Control System aka “pings”
PGNCS w/ AGC @ Lunar Module

11.
AGC: Apollo Guidance Computer
• Digital computer = DSKY + Block I/II
• Both on CM and LM
• Guidance + navigation + control
• NASA deep space net > vector > AGC
• DSKY = numeric display & keypad
• Numbers display: vectors
e.g. space craft attitude & velocity delta
• Commands: verb & noun
two XX numbers w/ action & data
• Units: metrics (internal) > US (DSKY)
• 2xCM & 1xLM
• Block I/Block II = digital computer
• Developed by MIT in 1966 w/ Raytheon
• fridges > WW2 > defense

12.
AGC: Hardware
• Lead: Charles Stark Draper
• “father of inertial navigation”
• RAM 3.8kB (Apollo 14 reprogramming)
• ROM 74kB of LOL memory
• “little old lady” - core rope memory
• Registers: 4 central 15+1b + ~20 specific
• Instructions: 11, 3b+12b (opcode + addr)*
• Interrupts: 5, Bus: 16b RD + 16WR
• Logical module (not CPU):
• 4.100/2.800 (Block I/II) integrated circuits (1958)
ICs > logic modules > Block I/II
• Timing: 2.048 MHz referential + aux timers
• ~32kg, ~70W/55W + stand-by, 61x32x17cm
• Water cooling
RAM ROM
Logic module
ICs

13.
AGC: Software
• Lead: Margaret Hamilton (31) @ MIT
• Exec OS w/ 8 jobs
• Cooperative multi-tasking
• Interrupt driven priority* job waitlist
• Margaret:
• Coined term software engineering & set dev standards
• Designed virtual machine ~ robust sophisticated interpreter
• new (pseudo) instructions & lower memory consumption
• buffer overflow & cycle stealing handling (RAM w/o CPU)
• Her robust AGC design avoided Apollo 11 crash
• … when landing on the Moon: 3’ > radar (activated by mistake) >
overload (interrupts) > alarms > … but still running* + 2’’ from death
Necessary software and programming techniques did NOT exist > to be designed
Margaret Hamilton
lead Apollo flight software engineer

14.
AGC: Try it Yourself!
• AGC emulators:
• JavaScript
• http://svtsim.com/moonjs/agc.html
• Project Apollo NASSP emulator
• http://sourceforge.net/projects/nassp/
• Original AGC source code:
• https://code.google.com/p/virtualagc/
• Comments & thoughts & ideas:
• news.ycombinator.com

15.
Lessons Learned
• Simple
• Reliable
• Robust
• Efficient … design
• Improvise
• Handle failure gracefully
• Work with users astronauts on UX
• Unit tests prove your code
• Trust in skilled crew, not in computers
They would not let as fly the moon today…